In some motors, an armature rotates to make the transfer of electricity across the motor possible. The spinning of the armature often enables the motor shaft to also spin. Because the armature normally rotates or spins, it is usually mounted on ball bearings and a housing is usually placed around the armature and/or bearings to protect them from debris.
In other motors, an armature may be associated with gears or valves and a housing is usually employed to protect the armature, gears, or valves from debris in order to enable proper operation of these parts.
The housing for the armature is typically assembled in parts, where flattened disc 8 is welded or attached in any fashion to cylinder 12. In other embodiments, cylinder 12 is a cup (see FIGS. 1a-1b). These components may be cut from sheet metal and bent to achieve the shape shown, where cutting and bending often increase manufacturing time and labor. After the components are cut and bent, they further need to be assembled together.
Another way of providing an armature housing may be to machine the various pieces in addition to or instead of assembling the pieces together. Some methods include machining at least a part of cylinder 12 or disc 8.
However, making an armature housing in the manners described above presents several disadvantages. When assembling the parts together, a weak point may be introduced when attaching cylinder 12 to disc 8 and any mechanical failure is usually located at the junction between cylinder 12 and disc 8.
In addition, since an electromagnetic field typically flows from disc 8 to cylinder 12, a bottle neck frequently occurs at the juncture of disc 8 and cylinder 12 because disc 8 is of sheet metal and its thinness provides a small cross section through which the electromagnetic field may flow. As a consequence, such electromagnetic field will ordinarily be impeded.
Further, one can argue the orientation of the grain structure of disc 8 and cylinder 12 inhibits the flow of the electromagnetic field because the grain structure may be perpendicular or angular relative to the radially traveling electromagnetic field. Since disc 8 or cylinder 12 is usually cut from sheet metal, the orientation of the grain structure is usually not known and often is not predictable or adjustable.
With regard to machining parts of disc 8 or cylinder 12, such practice is normally labor intensive and usually time consuming because no more than several thousandths or hundredths of an inch may be removed at a time, and removing material at this rate often translates to long periods of time for producing a armature. Moreover, the lathes used for machining parts are often expensive and require a large amount of space for proper operation. Therefore, any benefits obtained from machining parts over assembling parts may be outweighed by the associated costs.
U.S. Pat. No. 4,217,567 appears in FIGS. 10 and 10A to relate to a simple soft iron plug or insert 75 with a conforming nose portion pressed as interference fit into the external hollow space formed by the inwardly extending pole portion 52. The plug 75 has the effect of increasing the flux-carrying capacity across the gap defined by the wall 60 of the bobbin 55. Substantially the same effect may be achieved, at still lower cost, in which the flux carrying plug means comprises one or more mild steel balls 76 pressed into the hollow external cavity defined by the pole portion 52.
U.S. Pat. No. 6,029,704 Kuroda et al. appears to disclose a press formed or cold forged steel plate and a hollow cylindrical housing. However, because Kuroda's housing is made from multiple parts and assembled, it does not efficiently conduct the electromagnetic field.
U.S. Pat. No. 4,365,223 to Fechant et al. relates to a housing that may be put together in pieces.
What is desired, therefore, is a method of making an armature housing that reduces weak points without sacrificing manufacturing efficiency. Another desire is a method of making an armature housing that enhances a flow of an electromagnetic field.